Individual containers of various sizes and made of e.g. cartonboard or plastics materials, so-called primary packs, are commonly grouped together in a fibreboard case, or secondary packing, for distribution purposes. A fibreboard case provides compression strength additional to that of the plurality of individual containers in the case as well as giving added protection by way of puncture resistance. Fibreboard cases are also readily conveyed and handled by mechanical handling equipment and offer the maximum surface area for displaying printed matter. Nevertheless fibreboard cases can represent a significant additional packaging cost over the cost of the individual container cost and many proposals have been made for reducing the area of fibreboard required in a case in order to reduce the total packaging cost. For example, where the individual containers such as cans or bottles have adequate compression strength it can be more economical to provide a multiple package comprising a shallow fibreboard tray enveloped with a plastics film to retain the containers in place. On the other hand, particularly where the individual containers have little or insufficient compression strength or a shallow tray is otherwise inadequate, various skeletal case designs have been proposed such as in U.S. Pat. No. 3,425,544 and U.S. Pat. No. 2,868,429 having two upstanding walls the full height of the package but these approach a full case again in concept.
Skeleton packs have also been proposed where compression strength is not important, for example in French No. 79 02523 (publication No. 2 416 625), where packages are held in a two sided pack of a bottom member and rear member by one or more straps formed out of the material of the pack itself. These packs have a sloping top flange on to the rear member shaped to the primary packs, which take the load in any stacking.
We have sought to maximise the material saving in skeleton packs that are designed for compression loading and have seen that where such packs are themselves to be grouped, as in pallet loads, a base to receive the primary packages and a rear member to take vertical load are in essentials all that is needed. If the packs are placed with the front of one adjacent to the back of the next, the rear member in effect acts as part of both packs as far as taking vertical loads goes.